Method of forming metal cups, out of which hollow metal bodies with closed bottom can be manufactured by further drawing



1957 HANS-JOA'CHIM NAGEL 2,314,853

METHOD OF FORMING METAL CUPS, OUT OF WHICH HOLLOW METAL BODIES WITH CLOSED BOTTOM CAN BE MANUFACTURED BY FURTHER DRAWING Filed Nov. 1, 1954 Fig.4

Fig.2 F593 W m 42 Fig.5 Fig.6

United States Patent METHOD OF FORNIING METAL CUPS, OUT OF WHICH HOLLOW METAL BODIES WITH CLOSED BOTTOM CAN BE MANUFACTURED BY FUR- THER DRAWING Hans-Joachim Nagel, Lubeck, Germany, assignor to Manufacture de Machins du Haut-Rhin, Mulhouse-Bourtz- Wiler, France Application November 1, 1954, Serial No. 466,141 2 Claims. (Cl. 29-534) This invention refers to the production of cup-shaped metal articles. Many attempts have been made so far to avoid punching loss when stamping out disks as starting material or blanks for making hollow bodies with closed bottom.

Methods are known in which: I

(1) blanks are cut from a round bar and thereupon upset between the interfaces so as to form circular semifinished flat pieces corresponding in thickness to the bottom of the intended hollow body. The heavy upsetting, however, makes an extraordinary demand on the starting material and very high rejects or waste must be reckoned with, these even counter-balancing any savings that have been made. Also the influence of the stamping edge acts unfavorably on the upsetting process;

(2) blanks are stamped from round bars and then formed into a hollow body by inserting a punch pressing it in the direction of rolling. The peculiarity of this method, however, involves extraordinary high specific load or pressure of the punch so that heavy wear of tools thereby caused renders the process uneeonornical. Also this method suffers from the disadvantage that inevitable cracks in the material on the stamping surface are occasionally pressed into the bottom of the hollow body and can no longer be recognized. Also any slag inclusions from the zone of segregation of the bar will be pressed into the bottom. For very small diameters the process is still more uneconomical than for large ones.

The present invention aims at an improved process of making metal cups, out of which hollow metal bodies can be manufactured by further drawing.

In order to retain the merits of known methods and to aviod their drawbacks, according to the invention it is contemplated that blanks substantially square in outline or shape be cut from rolled flat bar material, that said blanks are shaped into substantially circular bulged disks by means of a pressing device acting at right angles to the direction of rolling the initial material, a punch penetrating so far into the blank until the desired thickness of the bottom of the cup is approximately obtained, that the bulged diskin a following plastic pressing stage and by adopting a punch introduced in the corresponding dieis pressed by the shoulders of the punch so as to cause the material to flow away in the pressing direction of the punch, and centric cups will be formed.

The method according to the invention, for drawing cups adapted to serve for the manufacture of hollow metal bodies with closed bottom, is explained at least diagrammatically with reference to the accompanying drawing, in which:

Fig. 1 shows a view of a rolled flat bar from which blanks of substantially squ'are outline are cut off;

Fig. 2 is a sectional view of one of the blank plates;

Fig. 3 is a diametral section through a disk 12 first made from a blank plate;

Fig. 4 is a diametral section through a cup from which "ice hollow bodies with closed bottom may be manufactured by further drawing;

Fig. 5 is a plan view of the object in Fig. 2;

Fig. 6 is a plan view of the object in Fig. 3;

Fig. 7 is a plan view of the object in Fig. 4;

Fig. 8 shows diagrammatically the appliance for producing circular disks as in Figs. 3 and 6 in two working steps from the blank plates according to Figs. 2 and 5;

Fig. 9 shows diagrammatically the appliance for producing the cups as in Figs. 4 and 7 in two working steps from the disks according to Figs. 3 and 6.

From a flat bar 10 shown in Fig. 1, hot rolled in the direction of the arrow and which may be a flat-rolled round bar, blanks 11 as in Figs. 2 and 5 are cut off. These blank plates or billets exhibit a substantially square outline and are laid in a circular bore of a die 21 (see Fig. 8). Said bore 21 passes over a taper portion 22 in a constricted bore 23 wherein a cylindrical counter-punch is seated adapted to serve at the same time as ejector. The appliance includes a pressing punch 25 with tapered shoulder 26. Said punch 25, 26 is introduced into the bore 21 of the die in the direction of the arrow, thus forming at first the square blank disk 11 into a substantially circular disk 12 with bulged edge (Fig. 3). The punch then acts at right angles to the surface of the blank, i. e. at right angles to the direction of rolling the initial bar 10. The material displaced by the entering punch 25, 26 flows at first into the free spaces bounded by the circle 11a which circumscribes the blank plate 11. The latter is thus plastically formed into a substantially circular disk, the punch entering so far that the bottom thickness of the cup to be made will approximately be reached. Thereby the stress in the material is so slight that even heavy surface defects can scarcely prove to be injurious. Also in this initial working step according to Fig. 8 the amount of total deformation is so slight that no especially high demands have to be put regarding the plasticity of the material, in any case no higher demands than have to be required for the later deep-drawing operation. In addition, dangerous shearing cracks cannot form, inasmuch as the direction in which the major change of shape occurs is comparatively short. Because of the possibility of the material yielding freely, there is favorable forming efficiency and relatively small pressure stressing on the punch. The compact shape of the pressing punch avoids unfavorable lateral forces which might be caused by one-sided distribution of the material. In spite of the pressing being at right angles to the direction of rolling, there is perfect formation of the flow lines, even at the square lines lying transversely to the direction of rolling.

The bulged disk 12 as in Figs. 3 and 6 and resulting in the last phase of the working step according to Fig. 8 is shaped further into the desired form of a cup by a plastic pressing operation. This operation will cause the material lying inside the bulged disk 12 to flow away in the pressing direction under the action of an entering pressing punch to thus produce the form of cup shown in Figs. 4 and 7. For this purpose the bulged disk is laid in the bore of another die 30 passing over a taper portion 32 into a restricted bore 33. Said bore 33 has an ejector punch 34 seated therein.

The pressing punch 35 of said die has a tapered transition portion 36 and a cylindrical head 37. By pressing the punch 36 into the die 30, a cup 13 as shown in Figs. 4 and 7 will result from the bulged disk 12. Thereby any defects of the surface and in particular of the shearing surface will not move into the cup itself, but remain in the collar 13a that is formed, the outer edge of which is removed by subsequent trimming.

By adopting the known drawing methods, the finished hollow bodies may easily be manufactured from the cups 13. Suitable annealing between the different shaping steps will ensure adequate restoration of the capacity for plastic deformation of the material.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. The method of forming metal cups for the manufacture of hollow metal bodies comprising the steps of cutting a blank of substantially square outline from rolled, round-edged and fiat bar material, shaping said blank into substantially circular dished disk with bulged rim by forcing said blank in a die at right angles to the direction of rolling of said blank material until a predetermined final thickness of the bottom of the disk is approximately obtained, then applying drawing pressure to said bulged rim so as to cause the material to flow in pressing direction, whereby a cylindrical cup wall of substantially equal thickness throughout is formed extending from said bottom.

2. The method of forming metal cups for the manufacture of hollow metal bodies comprising the steps of cutting a blank of substantially square shape from rolled, round-edged and fiat bar material, applying pressure to said blank at right angles to the direction of rolling of said blank material to transform same into substantially circular and dished disk with offset bulged rim, until the diameter thereof corresponds approximately to the diagonal of said square blank and until a predetermined final thickness of the bottom of said disk is obtained, and then applying drawing pressure to said offset rim to thereby cause material to be displaced from the latter in pressing direction, until a substantially cylindrical cup wall which extends from said bottom is formed.

References Cited in the file of this patent UNITED STATES PATENTS 2,140,775 Talbot-Crosbie et al Dec. 20, 1938 2,415,940 Eckstein Feb. 18, 1947 2,462,851 Fawcett et al. Mar. 1, 1949 FOREIGN PATENTS 687,457 Great Britain Feb. 11, 1953 

